University of Uppsala, Department of Public Health and Social Sciences, Clinical Hypertension Research, Sweden.

Abstract

BACKGROUND:

Despite treatment, there is often a higher incidence of cardiovascular complications in patients with hypertension than in normotensive individuals. Inadequate reduction of their blood pressure is a likely cause, but the optimum target blood pressure is not known. The impact of acetylsalicylic acid (aspirin) has never been investigated in patients with hypertension. We aimed to assess the optimum target diastolic blood pressure and the potential benefit of a low dose of acetylsalicylic acid in the treatment of hypertension.

METHODS:

18790 patients, from 26 countries, aged 50-80 years (mean 61.5 years) with hypertension and diastolic blood pressure between 100 mm Hg and 115 mm Hg (mean 105 mm Hg) were randomly assigned a target diastolic blood pressure. 6264 patients were allocated to the target pressure < or =90 mm Hg, 6264 to < or =85 mm Hg, and 6262 to < or =80 mm Hg. Felodipine was given as baseline therapy with the addition of other agents, according to a five-step regimen. In addition, 9399 patients were randomly assigned 75 mg/day acetylsalicylic acid (Bamycor, Astra) and 9391 patients were assigned placebo.

FINDINGS:

Diastolic blood pressure was reduced by 20.3 mm Hg, 22.3 mm Hg, and 24.3 mm Hg, in the < or =90 mm Hg, < or =85 mm Hg, and < or =80 mm Hg target groups, respectively. The lowest incidence of major cardiovascular events occurred at a mean achieved diastolic blood pressure of 82.6 mm Hg; the lowest risk of cardiovascular mortality occurred at 86.5 mm Hg. Further reduction below these blood pressures was safe. In patients with diabetes mellitus there was a 51% reduction in major cardiovascular events in target group < or =80 mm Hg compared with target group < or =90 mm Hg (p for trend=0.005). Acetylsalicylic acid reduced major cardiovascular events by 15% (p=0.03) and all myocardial infarction by 36% (p=0.002), with no effect on stroke. There were seven fatal bleeds in the acetylsalicylic acid group and eight in the placebo group, and 129 versus 70 non-fatal major bleeds in the two groups, respectively (p<0.001).

INTERPRETATION:

Intensive lowering of blood pressure in patients with hypertension was associated with a low rate of cardiovascular events. The HOT Study shows the benefits of lowering the diastolic blood pressure down to 82.6 mm Hg. Acetylsalicylic acid significantly reduced major cardiovascular events with the greatest benefit seen in all myocardial infarction. There was no effect on the incidence of stroke or fatal bleeds, but non-fatal major bleeds were twice as common.